Extrinsic levels, diffusion, and unusual incorporation mechanism of lithium in GaN

Bernardini, Fabio; Fiorentini, Vincenzo

Extrinsic levels, diffusion, and unusual incorporation mechanism of lithium in GaN

Authors

Description

Results of a first-principles study of the Li impurity in GaN are presented. We find Li is a channel interstitial, with an onset for diffusion at T$\sim$ 600 K. Above this temperature, Li can transform to a Ga-substitutional acceptor by exothermic recombination with Ga vacancies. This process implies capture of at least one electron; therefore Li acts as an electron sink. Li$_{\rm Ga}$ is stable again interstitialcy, and has a shallow first ionization levels of 0.16 eV, and second ionization at 0.63 eV. Lattice locations and their temperature dependence are in close agreement with recent experiments.
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